Plasma arc torch tip

ABSTRACT

A plasma arc torch is provided that comprises a set of torch consumable components secured to a torch head, wherein a supply of cooling fluid flows coaxially through the torch to cool torch components and a supply of plasma gas and secondary gas flows through the torch to generate and stabilize a plasma stream for operations such as cutting workpieces. The torch consumable components, in part, comprise an electrode and a tip that include a variety of configurations for improved cooling, electrical contact, and attachment to adjacent torch components. Further, a consumables cartridge is provided for ease of use and replacement of the torch consumable components. Additionally, methods of operating the plasma arc torch at relatively high current levels are also provided by the present invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon U.S. Provisional Patent Application, Ser.No. 60/373,992, entitled “Plasma Arc Torch” filed Apr. 19, 2002, thecontents of which are incorporated herein by reference in their entiretyand continued preservation of which is requested.

FIELD OF THE INVENTION

The present invention relates generally to plasma arc torches and moreparticularly to tips and methods of use for automated, high currentplasma arc torches.

BACKGROUND OF THE INVENTION

Plasma arc torches, also known as electric arc torches, are commonlyused for cutting, marking, gouging, and welding metal workpieces bydirecting a high energy plasma stream consisting of ionized gasparticles toward the workpiece. In a typical plasma arc torch, the gasto be ionized is supplied to a distal end of the torch and flows past anelectrode before exiting through an orifice in the tip, or nozzle, ofthe plasma arc torch. The electrode has a relatively negative potentialand operates as a cathode. Conversely, the torch tip constitutes arelatively positive potential and operates as an anode. Further, theelectrode is in a spaced relationship with the tip, thereby creating agap, at the distal end of the torch. In operation, a pilot arc iscreated in the gap between the electrode and the tip, which heats andsubsequently ionizes the gas. Further, the ionized gas is blown out ofthe torch and appears as a plasma stream that extends distally off thetip. As the distal end of the torch is moved to a position close to theworkpiece, the arc jumps or transfers from the torch tip to theworkpiece because the impedance of the workpiece to ground is lower thanthe impedance of the torch tip to ground. Accordingly, the workpieceserves as the anode, and the plasma arc torch is operated in a“transferred arc” mode.

In automated plasma arc torch applications, the plasma arc torchoperates at current levels between approximately 30 amps and 1,000 ampsor more. At the higher current levels, the torch correspondinglyoperates at relatively high temperatures. Accordingly, torch componentsand consumable components must be properly cooled in order to preventdamage or malfunction and to increase the operating life and cuttingaccuracy of the plasma arc torch. To provide such cooling, high currentplasma arc torches are generally water cooled, although additionalcooling fluids may be employed, wherein coolant supply and return tubesare provided to cycle the flow of cooling fluid through the torch.Additionally, a variety of cooling and gas passageways are providedthroughout various torch components for proper operation of the plasmaarc torch. However, the flow of cooling fluids in plasma arc torches ofthe known art have been relatively limited due to the positioning andconfiguration of internal cooling passageways.

With automated plasma arc torches of the known art, concentricity ofcomponents within the torch, such as the electrode and the tip, ornozzle, is critical in order to maintain accuracy when cutting aworkpiece. Further, the electrode and the tip are commonly known asconsumable components, which must replaced after a certain period ofoperation due to wear and/or damage that occurs during operation.Accordingly, concentricity of such consumable components must bemaintained throughout the many replacements that occur over the life ofa plasma arc torch.

Additionally, when the consumable components are replaced, tools areoften required for removal due to the type of connection between theconsumable components and a torch head. For example, the consumablecomponents may be threaded into the torch head and tightened with awrench or other tool. As a result, the replacement of consumablecomponents is often time consuming and cumbersome for a plasma arc torchoperator. Moreover, each of the consumable components are typicallyreplaced on an individual basis, rather than all at once, thereby makingremoval and installation of several different consumable components atdifferent even more time consuming and cumbersome.

Accordingly, a need remains in the art for a plasma arc torch andassociated methods that improve cutting efficiency and accuracy. Afurther need exists for such a plasma arc torch and methods that providefor relatively quick and efficient replacement of consumable components,(e.g., electrode, tip), disposed therein.

SUMMARY OF THE INVENTION

Generally, the present invention provides a plasma arc torch thatcomprises a set of torch consumable components secured to a torch head.The torch head comprises an anode body that is in electricalcommunication with the positive side of a power supply and a cathodethat is in electrical communication with the negative side of the powersupply. The cathode is further surrounded by a central insulator toinsulate the cathode from the anode body, and similarly, the anode bodyis surrounded by an outer insulator to insulate the anode body from ahousing, which encapsulates and protects the torch head and itscomponents from the surrounding environment during operation. The torchhead is further adjoined with a coolant supply tube, a plasma gas tube,a coolant return tube, and a secondary gas tube, wherein plasma gas andsecondary gas are supplied and cooling fluid is supplied and returnedfor operation of the plasma arc torch. Furthermore, a negative leadconnection is provided through the plasma gas tube or a liquid tube tothe cathode, and a pilot signal connection is provided through the anodebody to a torch cap.

The torch consumable components comprise an electrode, a tip, a spacer,a distal anode member, a central anode member, a baffle, a secondarycap, a shield cap, and a secondary spacer, which are housed by acartridge body in one form of the present invention. The tip, centralanode member, and distal anode member are anodic elements that comprisea portion of the positive side of the power supply, whereas theelectrode is a cathodic element that comprises a portion of the negativeside of the power supply. Accordingly, the spacer is disposed betweenthe electrode and the tip and provides electrical separation between theanodic and cathodic sides of the power supply, in addition to certaingas distributing functions as described in greater detail below. Thebaffle is disposed between the distal anode member and the shield capand provides for cooling fluid distribution during operation. Thesecondary cap is disposed distally from the tip and provides forsecondary gas distribution, and the secondary spacer provides spacingbetween the tip and the secondary cap. Additionally, the shield capsurrounds the other consumable components and is secured to a torch headusing a locking ring or other attachment member as described in greaterdetail below.

In another form of the present invention, the consumable componentsfurther comprise a coolant seal and guide disposed between the tip andthe secondary cap to direct and control the flow of cooling fluid. Theelectrode is centrally disposed within the cartridge body and is inelectrical contact with the cathode along an interior portion of theelectrode. The electrode and cathode are configured such that apassageway is formed therebetween for the passage of a cooling fluidproximate, or through an adjacent vicinity of, the electrical contact.The electrode further defines a central cavity that is in fluidcommunication with the coolant tube such that the cathode and electrode,along with other torch components, are properly cooled during operation.Further, the cartridge body generally distributes cooling fluid, plasmagas, and secondary gas, while providing separation or dielectric betweenvarious torch components as described in the detailed description thatfollows. Moreover, the fluid (cooling, plasma, secondary) is distributedin a coaxial flow between various torch components, which increases thetotal amount of flow and cooling within the plasma arc torch.

As used herein, the term “coaxial” shall be construed to mean a flowthat is annular and that flows in the same direction at any given radiallocation from the central longitudinal axis of the plasma arc torch.Additionally, the term “annular” shall be construed to mean a flow thatis distributed circumferentially about the central longitudinal axis ofthe plasma arc torch (although not necessarily continuously). Therefore,coaxial flow is a flow that is distributed circumferentially about thecentral longitudinal axis of the torch and that is flowing in the samedirection at any radial location from the central longitudinal axis. Forexample, a flow that crosses over the central longitudinal axis of theplasma arc torch such as that described in U.S. Pat. Nos. 5,396,043 and5,653,896, incorporated herein by reference) is not a coaxial flow.Coaxial flow is shown and described in greater detail in the detaileddescription that follows.

The tip is disposed distally from the electrode and is separatedtherefrom by the spacer. Similarly, the secondary cap is disposeddistally from the tip and is separated therefrom by the secondaryspacer. The distal anode member is generally disposed around the tip andis in electrical contact with both the tip and the central anode member.The tip and distal anode member are configured such that a passageway isformed therebetween for the passage of a cooling fluid proximate, orthrough an adjacent vicinity of, the electrical contact. Further, thecentral anode member is in electrical contact with the anode body withinthe torch head for electrical continuity within the positive, or anodicside of the power supply. Additionally, the baffle is disposed aroundthe distal anode member, and the shield cup is disposed around thebaffle. Accordingly, passageways are formed between the cartridge bodyand the distal anode member, and between the distal anode member and thebaffle for cooling fluid flow. Similarly, a passage is formed betweenthe baffle and the shield cup for secondary gas flow.

In other forms, several electrode and tip configurations are providedthat improve cooling, provide electrical continuity through the cathodeand anode side of the power supply, respectively, and that provideefficient attachment of the electrode and tip to the plasma arc torch.Additionally, configurations for consumable cartridges are provided,wherein a single cartridge containing one or more consumable componentsis removed and replaced when the one or more consumable componentsrequire replacement, rather than replacing individual consumablecomponents one at a time. Moreover, configurations for securing thetorch head to adjacent components such as a positioning tube are alsoprovided by other forms of the present invention.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of a plasma arc torch constructed inaccordance with the principles of the present invention;

FIG. 2 is an exploded perspective view of a plasma arc torch constructedin accordance with the principles of the present invention;

FIG. 3 is a longitudinal cross-sectional view, taken along line A—A ofFIG. 1, of the plasma arc torch in accordance with the principles of thepresent invention;

FIG. 4 is an exploded longitudinal cross-sectional view of the plasmaarc torch of FIG. 3 in accordance with the principles of the presentinvention;

FIG. 5 is an enlarged longitudinal cross-sectional view of a distalportion of the plasma arc torch of FIG. 3 in accordance with theprinciples of the present invention;

FIG. 6 is a longitudinal cross-sectional view of torch consumablecomponents constructed in accordance with the principles of the presentinvention;

FIG. 7 is a cross-sectional view of anode members constructed inaccordance with the principles of the present invention;

FIG. 8 is a perspective view of a cartridge body illustrating flexibletabs for a central anode member constructed in accordance with theprinciples of the present invention;

FIG. 9 a is a longitudinal cross-sectional view of a plasma arc torchillustrating coaxial flow in accordance with the principles of thepresent invention;

FIG. 9 b is a lateral cross-sectional view of a plasma arc torchillustrating coaxial flow in accordance with the principles of thepresent invention;

FIG. 10 is a perspective view of a torch cap of a plasma arc torch andconstructed in accordance with the principles of the present invention;

FIG. 11 is a cutaway perspective view of a plasma arc torch illustratingfluid passageways in accordance with the principles of the presentinvention;

FIG. 12 a is a cutaway perspective view of an electrode constructed inaccordance with the principles of the present invention;

FIG. 12 b is a perspective cutaway exploded view of a cathode within atorch head and an electrode constructed in accordance with theprinciples of the present invention;

FIG. 12 c is a cross-sectional view of an electrode disposed around acathode in accordance with the principles of the present invention;

FIG. 12 d is a lateral cross-sectional view, taken along line B—B ofFIG. 12 c, illustrating adjacent perimeter surfaces between an electrodeand a cathode in accordance with the principles of the presentinvention;

FIG. 13 a is a perspective view of a second embodiment of an electrodeconstructed in accordance with the principles of the present invention;

FIG. 13 b is a longitudinal cross-sectional view of the electrode of thesecond embodiment secured within a plasma arc torch in accordance withthe principles of the present invention;

FIG. 13 c is a lateral cross-sectional view of the electrode of thesecond embodiment secured within a plasma arc torch in accordance withthe principles of the present invention;

FIG. 14 a is a perspective view of a third embodiment of an electrodeconstructed in accordance with the principles of the present invention;

FIG. 14 b is a longitudinal cross-sectional view of the third electrodeembodiment secured within a plasma arc torch in accordance with theprinciples of the present invention;

FIG. 15 is a longitudinal cross-sectional view of a fourth embodiment ofan electrode secured within a plasma arc torch and constructed inaccordance with the principles of the present invention;

FIG. 16 is a longitudinal cross-sectional view of a fifth embodiment ofan electrode secured within a plasma arc torch and constructed inaccordance with the principles of the present invention;

FIG. 17 a is a longitudinal cross-sectional view of a fluid passagewayformed in a cathode adjacent electrical contact with an electrode andconstructed in accordance with the teachings of the present invention;

FIG. 17 b is a lateral cross-sectional view, taken along line C—C ofFIG. 17 a, of the cathode and electrode in accordance with theprinciples of the present invention;

FIG. 17 c is a longitudinal cross-sectional view of a fluid passagewayformed by a third element between a cathode and an electrode inaccordance with the principles of the present invention;

FIG. 17 d is a longitudinal cross-sectional view of a fluid passagewayformed by a helical flute between a cathode and an electrode inaccordance with the principles of the present invention;

FIG. 17 e is a longitudinal cross-sectional view of a fluid passagewayformed through a cathode and an electrode in accordance with theprinciples of the present invention;

FIG. 17 f is a longitudinal cross-sectional view of a fluid passagewayformed through an electrode in accordance with the principles of thepresent invention;

FIG. 18 is a longitudinal cross-sectional view of an electrode holderconstructed in accordance with the teachings of the present invention;

FIG. 19 is a perspective view of a tip constructed in accordance withthe principles of the present invention;

FIG. 20 is a side view of the tip of FIG. 19 in accordance with theprinciples of the present invention;

FIG. 21 is a longitudinal cross-sectional view of the tip, taken alongline D—D of FIG. 20, in accordance with the principles of the presentinvention;

FIG. 22 is a top view of the tip of FIG. 19 in accordance with theprinciples of the present invention;

FIG. 23 is a cross-sectional view of the tip disposed adjacent a distalanode member in accordance with the principles of the present invention;

FIG. 24 a is a cross-sectional view of a fluid passageway formed in atip adjacent electrical contact with the distal anode member inaccordance with the principles of the present invention;

FIG. 24 b is a cross-sectional view, taken along line E—E of FIG. 24 a,of the tip and distal anode member in accordance with the principles ofthe present invention;

FIG. 24 c is a cross-sectional view of a fluid passageway formed by athird member disposed between a tip and a distal anode member inaccordance with the principles of the present invention;

FIG. 24 d is a cross-sectional view of a fluid passageway formed betweenby a helical flute between a tip and a distal anode member in accordancewith the principles of the present invention;

FIG. 25 a is a perspective view of a secondary cap constructed inaccordance with the principles of the present invention;

FIG. 25 b is a top view of a secondary cap constructed in accordancewith the principles of the present invention;

FIG. 26 a is a longitudinal side cross-sectional view of secondary gasbleed passageways constructed in accordance with the principles of thepresent invention;

FIG. 26 b is a top view of a shield cap comprising secondary gas bleedpassageways and constructed in accordance with the principles of thepresent invention;

FIG. 26 c is a longitudinal side cross-sectional view of an alternatetorch embodiment for bleeding secondary gas and constructed inaccordance with the principles of the present invention;

FIG. 27 a is a perspective view of a secondary cap spacer constructed inaccordance with the principles of the present invention;

FIG. 27 b is a side view of the secondary spacer constructed inaccordance with the principles of the present invention;

FIG. 28 a is a perspective view of a consumables cartridge constructedin accordance with the principles of the present invention;

FIG. 28 b is a longitudinal cross-sectional view of the consumablescartridge, taken along line E—E of FIG. 28 a, in accordance with theprinciples of the present invention;

FIG. 29 is a longitudinal cross-sectional view of a second embodiment ofa consumables cartridge constructed in accordance with the principles ofthe present invention;

FIG. 30 is a longitudinal cross-sectional view of a stepped cartridgeattachment illustrating cooling fluid passageways and constructed inaccordance with the principles of the present invention;

FIG. 31 is a longitudinal cross-sectional view of a stepped cartridgeattachment illustrating gas passageways and constructed in accordancewith the principles of the present invention;

FIG. 32 a is a longitudinal cross-sectional view of a face sealcartridge attachment illustrating cooling fluid passageways andconstructed in accordance with the principles of the present invention;

FIG. 32 b is a longitudinal cross-sectional view of a face sealcartridge attachment illustrating gas passageways and constructed inaccordance with the principles of the present invention;

FIG. 33 a is a longitudinal cross-sectional view of a straight cartridgeattachment illustrating cooling fluid passageways and constructed inaccordance with the principles of the present invention;

FIG. 33 b is a longitudinal cross-sectional view of a straight cartridgeattachment illustrating gas passageways and constructed in accordancewith the principles of the present invention;

FIG. 34 a is an enlarged longitudinal cross-sectional view of aball-lock mechanism connected and constructed in accordance with theprinciples of the present invention;

FIG. 34 a is an enlarged longitudinal cross-sectional view of aball-lock mechanism disconnected and constructed in accordance with theprinciples of the present invention;

FIG. 35 a is a longitudinal cross-sectional view of a torch head havingalignment geometry and constructed in accordance with the principles ofthe present invention;

FIG. 35 b is a top view of a torch head having alignment geometry andconstructed in accordance with the principles of the present invention;

FIG. 36 is a longitudinal cross-sectional view of a second plasma arctorch embodiment constructed in accordance with the teachings of thepresent invention;

FIG. 37 is a longitudinal cross-sectional view of a torch head of thesecond plasma arc torch embodiment in accordance with the principles ofthe present invention;

FIG. 38 is a longitudinal cross-sectional view of consumable componentsof the second plasma arc torch embodiment in accordance with theprinciples of the present invention;

FIG. 39 a is a perspective view of a cartridge body constructed inaccordance with the teachings of the present invention;

FIG. 39 b is a proximal perspective view of a cartridge body constructedin accordance with the teachings of the present invention;

FIG. 39 c is a top view of a cartridge body constructed in accordancewith the teachings of the present invention;

FIG. 39 d is a bottom view of a cartridge body constructed in accordancewith the teachings of the present invention;

FIG. 40 is a perspective view of a central anode member constructed inaccordance with the teachings of the present invention;

FIG. 41 is a perspective view of a distal anode member constructed inaccordance with the teachings of the present invention;

FIG. 42 is an exploded perspective view of a tip, a tip guide, and a tipseal constructed in accordance with the teachings of the presentinvention;

FIG. 43 is a side view of a tip assembly constructed in accordance withthe teachings of the present invention;

FIG. 44 is a longitudinal cross-sectional view of a plasma arc torchillustrating the cooling fluid flow in accordance with the principles ofthe present invention;

FIG. 45 is a longitudinal cross-sectional view of a plasma arc torchillustrating the plasma gas flow in accordance with the principles ofthe present invention;

FIG. 46 is a longitudinal cross-sectional view of a plasma arc torchillustrating the secondary gas flow in accordance with the principles ofthe present invention;

FIG. 47 a is a longitudinal cross-sectional view of a consumablescartridge constructed in accordance with the teachings of the presentinvention;

FIG. 47 b is a longitudinal cross-sectional view of a second embodimentof a consumables cartridge constructed in accordance with the teachingsof the present invention;

FIG. 47 c is a longitudinal cross-sectional view of a third embodimentof a consumables cartridge constructed in accordance with the teachingsof the present invention;

FIG. 47 d is a longitudinal cross-sectional view of a fourth embodimentof a consumables cartridge constructed in accordance with the teachingsof the present invention;

FIG. 47 e is a longitudinal cross-sectional view of a fifth embodimentof a consumables cartridge constructed in accordance with the teachingsof the present invention;

FIG. 47 f is a longitudinal cross-sectional view of a sixth embodimentof a consumables cartridge constructed in accordance with the teachingsof the present invention;

FIG. 48 a is a longitudinal cross-sectional view of a consumablesassembly constructed in accordance with the teachings of the presentinvention;

FIG. 48 b is a longitudinal cross-sectional view of a second embodimentof a consumables assembly in accordance with the principles of thepresent invention;

FIG. 48 c is a longitudinal cross-sectional view of a third embodimentof a consumables assembly in accordance with the principles of thepresent invention;

FIG. 48 d is a longitudinal cross-sectional view of a fourth embodimentof a consumables assembly in accordance with the principles of thepresent invention;

FIG. 48 e is a longitudinal cross-sectional view of a fifth embodimentof a consumables assembly in accordance with the principles of thepresent invention;

FIG. 48 f is a longitudinal cross-sectional view of a sixth embodimentof a consumables assembly in accordance with the principles of thepresent invention;

FIG. 48 g is a longitudinal cross-sectional view of a seventh embodimentof a consumables assembly in accordance with the principles of thepresent invention;

FIG. 49 is an exploded longitudinal cross-sectional view of torch headconnections constructed in accordance with the teachings of the presentinvention;

FIG. 50 is a longitudinal cross-sectional view of another plasma arctorch embodiment constructed in accordance with the teachings of thepresent invention; and

FIG. 51 is a schematic view illustrating a plasma arc torch employedwithin a plasma arc torch cutting system in accordance with the variousembodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiments is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

Referring to the drawings, a plasma arc torch according to the presentinvention is illustrated and indicated by reference numeral 10 in FIG. 1through FIG. 6. The plasma arc torch 10 generally comprises a torch head12 disposed at a proximal end 14 of the plasma arc torch 10 and aplurality of consumable components 16 secured to the torch head 12 anddisposed at a distal end 18 of the plasma arc torch 10 as shown.

As used herein, a plasma arc torch should be construed by those skilledin the art to be an apparatus that generates or uses plasma for cutting,welding, spraying, gouging, or marking operations, among others, whethermanual or automated. Accordingly, the specific reference to plasma arccutting torches or plasma arc torches should not be construed aslimiting the scope of the present invention. Furthermore, the specificreference to providing gas to a plasma arc torch should not be construedas limiting the scope of the present invention, such that other fluids,e.g. liquids, may also be provided to the plasma arc torch in accordancewith the teachings of the present invention. Additionally, proximaldirection or proximally is the direction towards the torch head 12 fromthe consumable components 16 as depicted by arrow A′, and distaldirection or distally is the direction towards the consumable components16 from the torch head 12 as depicted by arrow B′.

Torch Head

Referring more specifically to FIG. 5, the torch head 12 includes ananode body 20 that is in electrical communication with the positive sideof a power supply (not shown), and a cathode 22 that is in electricalcommunication with the negative side of the power supply. The cathode 22is further surrounded by a central insulator 24 to insulate the cathode22 from the anode body 20, and similarly, the anode body 20 issurrounded by an outer insulator 26 to insulate the anode body 20 from ahousing 28, which encapsulates and protects the torch head 12 and itscomponents from the surrounding environment during operation. The torchhead 12 is further adjoined with a coolant supply tube 30, a plasma gastube 32, a coolant return tube 34, and a secondary gas tube 35 (shown intheir entirety in FIGS. 1 and 2), wherein plasma gas and secondary gasare supplied to and cooling fluid is supplied to and returned from theplasma arc torch 10 during operation as described in greater detailbelow.

The cathode 22 preferably defines a cylindrical tube having a centralbore 36 that is in fluid communication with the coolant supply tube 30at a proximal portion 38 of the torch head 12. The central bore 36 isalso in fluid communication with a cathode cap 40 and a coolant tube 42disposed at a distal portion 44 of the torch head 12. Generally, thecoolant tube 42 serves to distribute the cooling fluid and the cathodecap 40 protects the distal end of the cathode 22 from damage duringreplacement of the consumable components 16 or other repairs. As furthershown, the cathode 22 comprises an internal annular ring 46 that engagesa proximal groove 48 formed in the cathode cap 40. As further shown, aflexible collar 49 formed on the cathode cap 40 engages the annular ring46 such that the cathode cap 40 is properly secured within the cathode22. To secure the coolant tube 42, the cathode cap 40 defines aninternal shoulder 50 against which an annular ring 52 of the coolanttube 42 abuts. Further, the coolant tube 42 defines an o-ring groove 54that houses an o-ring 56 to seal and retain the interface between thecathode cap 40 and the coolant tube 42. Preferably, the coolant tube 42is formed of a durable material such as stainless steel, and the cathodecap 40 is insulative and is preferably formed of a material such asTorlon® or other material known in the art that is also capable ofoperating at relatively high temperatures (For example, approximately250° C. to approximately 350° C.).

The central insulator 24 preferably defines a cylindrical tube having aninternal bore 60 that houses the cathode 22 as shown. The cathode 22defines a proximal external shoulder 62 that abuts a proximal internalshoulder 64 of the central insulator 24 to position of the cathode 22along the central longitudinal axis X of the plasma arc torch 10.Further, the cathode 22 comprises an external o-ring groove 65 thathouses an o-ring 66 to seal the interface between the cathode 22 and thecentral insulator 24. The central insulator 24 is further disposedwithin the anode body 20 as shown along a central portion 68 and alsoengages a torch cap 70 that accommodates the coolant supply tube 30, theplasma gas tube 32, and the coolant return tube 34.

Electrical continuity for electric signals such as a pilot return isprovided through a contact 72 disposed between the torch cap 70 and theanode body 20. The contact 72 comprises a proximal flange 74 that abutsa recessed shoulder 76 formed in the torch cap 70 and a distal end 78that engages the anode body 20 as shown. Preferably, the contact 72 isthreaded into the anode body 20, however, other attachment methods suchas a press fit or soldering may also be used while remaining within thescope of the present invention. Additionally, a distal annular wall 80of the torch cap 70 abuts an o-ring 82 disposed within an o-ring groove84 within the outer insulator 26 to seal the interface between the torchcap 70 and the outer insulator 26. Similarly, a distal internal wall 86of the housing 28 abuts an o-ring 88 disposed within an o-ring groove 90of the consumable components 16 to seal an interface between the housing28 and the consumable components 16. Additional o-ring grooves 92 withcorresponding o-rings (not shown) are provided between a plurality ofinterfaces as shown to seal the fluid (plasma gas, secondary gas,cooling fluid) passageways and are not described in further detailherein for purposes of clarity.

Alternately, electrical continuity for the pilot return or otherelectrical signals may be provided directly through an interface betweenthe torch cap 70 and the anode body 20 using detents engaging a shoulderas shown and described in U.S. Pat. No. 6,163,008, which is commonlyassigned with the present application and the contents of which areincorporated herein by reference. The detents may be incorporated on thetorch cap 70 or the anode body 20 with a corresponding shoulder and capon the anode body 20 or torch cap 70, respectively. Further, the detentsprovide a connection that is relatively simple and easy to engage anddisengage. Similarly, other components within the plasma arc torch 10may also employ the detents and shoulder for their respectiveconnections while remaining within the scope of the present invention.

Consumable Components

The consumable components 16, which are shown in greater detail in FIG.6, comprise an electrode 100, a tip 102, and a spacer 104 disposedbetween the electrode 100 and the tip 102 as shown. The spacer 104provides electrical separation between the cathodic electrode 100 andthe anodic tip 102, and further provides certain gas distributingfunctions as described in greater detail below. The consumablecomponents 16 further comprise a cartridge body 106, which generallyhouses and positions the other consumable components 16. The cartridgebody 106 also distributes plasma gas, secondary gas, and cooling fluidduring operation of the plasma arc torch 10, which is described ingreater detail below. Additionally, the consumable components 16comprise a distal anode member 108 and a central anode member 109 toform a portion of the anodic side of the power supply by providingelectrical continuity to the tip 102. A baffle 110 is also showndisposed between the distal anode member 108 and a shield cap 114, whichforms fluid passageways for the flow of a cooling fluid as described ingreater detail below. Further, the consumable components 16 comprise asecondary cap 112 for the distribution of the secondary gas and asecondary spacer 116 that separates the secondary cap 112 from the tip102. A locking ring 117 is shown disposed around the proximal endportion of the consumable components 16, which is used to secure theconsumable components 16 to the torch head 12 (not shown).

The electrode 100 is centrally disposed within the cartridge body 106and is in electrical contact with the cathode 22 (FIG. 5) along aninterior portion 118 of the electrode 100 as described in greater detailbelow. The electrode 100 further defines a distal cavity 120 that is influid communication with the coolant tube 42 (FIG. 5) and an externalshoulder 122 that abuts the spacer 104 for proper positioning along thecentral longitudinal axis X of the plasma arc torch 10. The cartridgebody 106 further comprises an internal annular ring 124 that abuts aproximal end 126 of the electrode 100 for proper positioning of theelectrode 100 along the central longitudinal axis X of the plasma arctorch 10. Additionally, the connection between the cartridge body 106and the cathode 22 may employ the detents and shoulder as previouslydescribed while remaining within the scope of the present invention. Inaddition to positioning the various consumable components 16, thecartridge body 106 also separates anodic member (e.g., central anodemember 109) from cathodic members (e.g., electrode 100). Accordingly,the cartridge body 106 is an insulative material such as PEEK® or othersimilar material commonly known in the art that is further capable ofoperating at relatively high temperatures.

For the distribution of cooling fluid as described in greater detailbelow, the cartridge body 106 defines an upper chamber 128 and aplurality of passageways 130 that extend through the cartridge body 106and into an inner cooling chamber 132 formed between the cartridge body106 and the distal anode member 108. Preferably, the passageways 130(shown dashed) are angled radially outward in the distal direction fromthe upper chamber 128 (shown dashed) to reduce any amount of dielectriccreep that may occur between the electrode 100 and the distal anodemember 108. Additionally, outer axial passageways 133 are formed in thecartridge body 106 that provide for a return of the cooling fluid, whichis further described below. For the distribution of plasma gas, thecartridge body 106 defines a plurality of distal axial passageways 134that extend from a proximal face 136 of the cartridge body 106 to adistal end 138 thereof, which are in fluid communication with the plasmagas tube 32 (not shown) and passageways formed in the tip 102 asdescribed in greater detail below. Additionally, a plurality of proximalaxial passageways 140 are formed through the cartridge body 106 thatextend from a recessed proximal face 142 to a distal outer face 144 forthe distribution of a secondary gas, which is also described in greaterdetail below. Near the distal end of the consumables cartridge 16, anouter fluid passage 148 is formed between the distal anode member 108and the baffle 110 for the return of cooling fluid as described ingreater detail below. Accordingly, the cartridge body 106 performs bothcooling fluid distribution functions in addition to plasma gas andsecondary gas distribution functions.

As shown in FIGS. 5 and 6, the distal anode member 108 is disposedbetween the cartridge body 106 and the baffle 110 and is in electricalcontact with the tip 102 at a distal portion and with the central anodemember 109 at a proximal portion. Further, the central anode member 109is in electrical contact with a distal portion of the anode body 20.Preferably, a canted coil spring (not shown) is disposed within a groove146 to provide electrical contact between the central anode member 109and the anode body 20. Alternately, electrical continuity for the pilotreturn or other electrical signals may be provided directly through aninterface between the central anode member 109 and the anode body 20using detents engaging a shoulder as shown and described in U.S. Pat.No. 6,163,008, which is commonly assigned with the present applicationand the contents of which are incorporated herein by reference. Thedetents may be incorporated on the central anode member 109 or the anodebody 20 with a corresponding shoulder and cap on the anode body 20 orcentral anode member 109, respectively. Accordingly, the anode body 20,the distal anode member 108, the central anode member 109, and the tip102 form the anode, or positive, potential for the plasma arc torch 10.

The detents are illustrated in greater detail in FIGS. 7 and 8, whereinthe central anode member 109 is preferably secured to the cartridge body106 using detents 260 as shown. (Certain portions of the plasma arctorch 10 and the cartridge body 106 are omitted for purposes ofclarity). The detents 260 extend radially inward to engage a shoulder262 formed at the proximal end of the cartridge body 106 that extendsradially outward as shown. Alternately, the detents 260 may extendradially outward while the shoulder 262 extends radially inward inanother form of the present invention. Additionally, the detents 260 areformed in flexible tabs 264 of the central anode member 109 as shown,wherein the tabs 264 provide additionally flexibility for assembly ofthe central anode member 109 to the cartridge body 106.

Referring again to FIG. 6, the shield cap 114 surrounds the baffle 110as shown, wherein a secondary gas passage 150 is formed therebetween.Generally, the secondary gas flows from the proximal axial passageways140 formed in the cartridge body 106 into the secondary gas passage 150and through the secondary cap 112, as described in greater detail below,to stabilize the plasma stream exiting the secondary cap 112 inoperation. The shield cap 114 further positions the secondary cap 112,wherein the secondary cap 112 defines an annular shoulder 152 thatengages a conical interior surface 154 of the shield cap 114.Alternately, the shield cap 114 may define a rounded corner (not shown)rather than a conical surface to engage the annular shoulder 152 for animproved fit. Similarly, the secondary cap 112 may alternately define arounded corner that engages the conical interior surface 154 of theshield cap 114.

The secondary spacer 116 spaces and insulates the secondary cap 112 fromthe tip 102. Preferably, the secondary spacer 116 comprises a proximalface 156 that abuts an annular shoulder 158 of the tip 102 and a distalface 160 and shoulder 162 that abut an internal shoulder 164 of thesecondary cap 112. As further shown, a secondary gas chamber 167 isformed between the tip 102 and the secondary cap 112, wherein thesecondary gas is distributed to stabilize the plasma stream, asdescribed in greater detail below. The secondary cap 112 furthercomprises a central exit orifice 168 through which the plasma streamexits and a recessed face 170 that contributes to controlling the plasmastream. Additionally, bleed passageways 171 may be provided through thesecondary cap 112, which are shown as axial holes although otherconfigurations may be employed as described in greater detail below, tobleed off a portion of the secondary gas for additional cooling duringoperation.

The tip 102 is electrically separated from the electrode 100 by thespacer 104, which results in a plasma chamber 172 being formed betweenthe electrode 100 and the tip 102. The tip 102 further comprises acentral exit orifice 174, through which a plasma stream exits duringoperation of the plasma arc torch 10 as the plasma gas is ionized withinthe plasma chamber 172. Accordingly, the plasma gas enters the tip 102through an annular ring 176 and swirl holes 178, which are described ingreater detail below, formed through an interior wall 180 of the tip 102as shown.

As further shown, the locking ring 117 secures the consumable components16 to the torch head 12 when the plasma arc torch 10 is fully assembled.The locking ring 117 forms an internal shoulder 182 that engages anannular ring 184 formed on the cartridge body 106 and is preferablysecured to the torch head 12 through a threaded connection. Alternately,the torch head 12 may be secured to the torch consumable components 16using a dual pitch locking connector as shown and described in copendingapplication Ser. No. 10/035,534 filed Nov. 9, 2001, which is commonlyassigned with the present application and the contents of which areincorporated herein by reference.

Cooling Fluid Flow

Referring again to FIGS. 5 and 6, in operation, the cooling fluid flowsdistally through the central bore 36 of the cathode 22, through thecoolant tube 42, and into the distal cavity 120 of the electrode 100.The cooling fluid then flows proximally through the proximal cavity 118of the electrode 100 to provide cooling to the electrode 100 and thecathode 22 that are operated at relatively high currents andtemperatures. The cooling fluid continues to flow proximally to theradial passageways 130 in the cartridge body 106, wherein the coolingfluid then flows through the passageways 130 and into the inner coolingchamber 132. The cooling fluid then flows distally towards the tip 102,which also operates at relatively high temperatures, in order to providecooling to the tip 102. As the cooling fluid reaches the distal portionof the distal anode member 108, the cooling fluid reverses directionagain and flows proximally through the outer fluid passage 148 and thenthrough the outer axial passageways 133 in the cartridge body 106. Thecooling fluid then flows proximally through recessed walls 190 (showndashed) and axial passageways 192 (shown dashed) formed in the anodebody 20. Once the cooling fluid reaches a proximal shoulder 193 of theanode body 20, the fluid flows through the coolant return tube 34 and isrecirculated for distribution back through the coolant supply tube 30.

As a result, the cooling fluid flow is “coaxial,” which is illustratedin FIGS. 9 a and 9 b, wherein the flow of the cooling fluid is shown bythe heavy dark arrows. As shown, the cooling fluid generally flowsdistally, then proximally, then distally again, and then proximally toreturn the cooling fluid for recirculation. Additionally, the coolingfluid flows annularly, which is best shown in FIG. 9 b, wherein the flowis generally annular about the central longitudinal axis X of the plasmaarc torch 10. As further shown, the flow is in the same direction (i.e.proximal or distal) at each radial location K, L, M, and N. At radiallocation K, the cooling fluid is flowing distally; at radial location L,the cooling fluid is flowing proximally; at radial location M, thecooling fluid is flowing distally, and at radial location N, the coolingfluid is flowing proximally again. Also note that the cooling fluid doesnot flow radially to cross the central longitudinal axis X of the plasmaarc torch 10 for fluid return. Rather, the cooling fluid flows coaxiallyand progressively outwardly to cool components of the plasma arc torch10 and to return for recirculation.

Therefore, as used herein, the term coaxial flow shall be construed tomean a flow that is annular and that flows in the same direction at anygiven radial location from the central longitudinal axis X of the plasmaarc torch 10. Additionally, the term “annular” shall be construed tomean a flow that is distributed circumferentially about the centrallongitudinal axis of the plasma arc torch. Therefore, coaxial flow is aflow that is distributed circumferentially about the centrallongitudinal axis of the torch and that is flowing in the same directionat any radial location from the central longitudinal axis. Accordingly,a coaxial cooling flow is provided by the present invention toefficiently cool components throughout the plasma arc torch 10.

Plasma Gas Flow

Referring to FIGS. 5 and 6, the plasma gas generally flows distally fromthe plasma gas tube 32, through an axial passage 194 (shown dashed) inthe torch cap 70, and into a central cavity 196 formed in the anode body20. The plasma gas then flows distally through axial passageways 198formed through an internal distal shoulder 200 of the anode body 20 andinto the distal axial passageways 134 formed in the cartridge body 106.The plasma gas then enters the plasma chamber 172 through passageways inthe tip 102, which are described in greater detail below, to form aplasma stream as the plasma gas is ionized by the pilot arc.

Secondary Gas Flow

Referring to FIGS. 5, 10, and 11, the secondary gas generally flowsdistally from the secondary gas tube 35 (shown in FIGS. 1 and 2) andthrough an axial passage 202 formed between an outer wall 204 of thetorch cap 70 and the housing 28. The secondary gas then continues toflow distally through axial passageways 206 formed through an annularextension 208 of the outer insulator 26 and into the proximal axialpassageways 140 of the cartridge body 106. The secondary gas then entersthe secondary gas passage 150 and flows distally between the baffle 110and the shield cap 114, through the distal secondary gas passage 209.Finally, the secondary gas enters the secondary gas plenum 167 throughpassageways formed in the secondary cap 112, which are described ingreater detail below, to stabilize the plasma stream that exits throughthe central exit orifice 174 of the tip 102.

Operation

In operation, the cathode or negative potential is carried by thecathode 22 and the electrode 100. The anode or positive potential iscarried by the anode body 20, the distal anode member 108, the centralanode member 109, and the tip 102. Therefore, when electric power isapplied to the plasma arc torch 10, a pilot arc is generated in the gapformed between the electrode 100 and the tip 102, within the plasmachamber 172. As the plasma gas enters the plasma chamber 172, the plasmagas is ionized by the pilot arc, which cause a plasma stream to formwithin the plasma chamber 172 and flow distally through the central exitorifice 174 of the tip 102. Additionally, the secondary gas flows intothe secondary gas plenum 167 and stabilizes the plasma stream uponexiting the central exit orifice 174 of the tip 102. As a result, ahighly uniform and stable plasma stream exits the central exit orifice168 of the secondary cap 112 for high current, high tolerance cuttingoperations.

Electrode Embodiments

Referring now to FIGS. 12 a through 18, the electrode 100 may comprise avariety of configurations for proper cooling, electrical contact withthe cathode 22, and attachment to the cartridge body 106. In theembodiments shown and described herein, cooling of the electrode 100 isprovided proximate, or through an adjacent vicinity of, the electricalcontact between the electrode 100 and the cathode 22, which is furtherdefined in the description that follows.

In a first embodiment as shown in FIGS. 12 a through 12 d, the electrode100 a defines flutes 220 and raised ribs 222. The flutes 220 form afluid passageway between the electrode 100 a and the cathode 22 a (bestshown in FIG. 12 d) for cooling proximate the electrical contact betweenthe electrode 100 a and the cathode 22 a. More specifically, the flutes220 produce a relatively high velocity flow proximate the interfacebetween the electrode 100 a and the cathode 22 a, where cooling iscritical. Additionally, the raised ribs 222 are in electrical contactwith an outer wall 224 of the cathode 22 a, which provides electricalcontinuity between the cathodic members (i.e. cathode, electrode) of theplasma arc torch 10. Preferably, the outer wall 224 defines a pluralityof axial tabs 226 as shown in FIG. 12 b such that the cathode cap 40 andthe coolant tube 42 may be more easily assembled within the cathode 22a.

Referring specifically to FIG. 12 d, which is a view showing the lateralinterface between the electrode 100 a and the cathode 22 a, theelectrode 100 a defines a perimeter surface 225 and the cathode 22 asimilarly defines a perimeter surface 227. The perimeter surfaces 225and 227 are thus defined by taking a section cut along a lateral planethrough the interface between the electrode 100 a and the cathode 22 aor other cathodic element. (The surfaces are shown in FIG. 12 d with aslight gap for illustration purposes only, and the perimeter surface 225of the electrode 100 a physically contacts the perimeter surface 227 ofthe cathode 22 a during operation). Accordingly, the perimeter surface225 of the electrode 100 a is adjacent the perimeter surface 227 of thecathode 22 a, wherein the adjacent perimeter surfaces 225 and 227provide both the electrical contact and the passage of a cooling fluid.Thus, a novel aspect of the present invention is providing both theelectrical contact and the passage of the cooling fluid through theadjacent perimeter surfaces. As a result, both cooling and electricalcontact are provided proximate, or in an adjacent vicinity to, oneanother, which provides for more efficient operation of the plasma arctorch 10.

As shown in FIGS. 13 a through 13 c, a second embodiment of theelectrode indicated as 100 b may alternately define axial passageways230 rather than the flutes 220, wherein the axial passageways 230produce the relatively high velocity flow of the cooling fluid thatflows proximally therethrough. Accordingly, the cooling fluid flowsproximally through the axial passageways 230 to cool the interfacebetween the electrode 100 b and the cathode 22 b. For electricalcontact, an internal wall 228 is formed within the electrode 100 b thatmakes contact with the outer wall 224 of the cathode 22 b.

Referring to FIG. 13 c, which is a lateral view through the interfacebetween the electrode 100 b and the cathode 22 b, the electrode 100 bdefines a perimeter surface 229 and the cathode 22 b defines a perimetersurface 331. Accordingly, the perimeter surface 229 of the electrode 100b is adjacent the perimeter surface 331 of the cathode 22 b. (Thesurfaces are shown in FIG. 13 c with a slight gap for illustrationpurposes only, and the perimeter surface 229 of the electrode 100 bphysically contacts the perimeter surface 331 of the cathode 22 b duringoperation). Although the adjacent perimeter surfaces 229 and 331 provideonly electrical contact in this form of the present invention, thepassage of cooling fluid through axial passageways 230 is proximate, orthrough an adjacent vicinity of the electrical contact as shown suchthat effective cooling of the interface between the electrode 100 b andthe cathode 22 b is achieved. For example, the distance P between theaxial passageways 230 and the perimeter surface 331 of the cathode 22 cis up to approximately 0.050 inches to define an adjacent vicinity inone form of the present invention. However, other distances may beemployed so long as the electrical interface between the electrode 100 cand the cathode 22 c is properly cooled by the cooling fluid flowingthrough the fluid passageways. Therefore, the terms “proximate” or“adjacent vicinity” as used herein with respect to cooling the interfacebetween the electrode 100 and the cathode 22 b shall be construed tomean along or within a close distance to the electrical contact suchthat effective cooling is achieved. Accordingly, the adjacent perimetersurfaces throughout the remaining electrode embodiments shall not beillustrated for purposes of clarity.

In a third embodiment of the electrode indicated as 100 c in FIGS. 14 aand 14 b, the electrode 100 c defines radial passageways 232 and axialslots 234 to provide cooling between the electrode 100 c and the cathode22 c. The cooling fluid generally flows proximally to the radialpassageways 232 and then proximally to the axial slots 234, wherein thecooling fluid exits the interface between the electrode 100 c and thecathode 22 c and proceeds through the passageways 130 as previouslydescribed. For electrical contact, an internal wall 236 is similarlyformed within the electrode 100 c that makes contact with the outer wall224 of the cathode 22 c. Accordingly, a perimeter surface of theelectrode 100 c is adjacent a perimeter surface of the cathode 22 c toform a fluid passageway for cooling proximate the electrical contact.

Referring now to FIG. 15, a fourth embodiment of the electrode indicatedas 100 d comprises an internal undercut 240 to provide additionalcooling of the electrode 100 d and the interface between the electrode100 d and the cathode 22 d. Additionally, the cathode 22 d definesradial passageways 242 that provide a return path for the cooling fluidto flow proximally between the coolant tube 42 d and the cathode 22 d asshown. Therefore, the cooling fluid flows distally through the coolanttube 42 d, proximally through the internal under cut 240, then radiallyinward through the radial passageways 242, and then proximally betweenthe coolant tube 42 d and the cathode 22 d for recirculation. Further,electrical contact is provided between an internal wall 244 of theelectrode 100 d and the outer wall 224 of the cathode 22 d. Accordingly,a fluid passageway is formed such that cooling is provided proximate theelectrical contact between the electrode 100 d and the cathode 22 d.Alternately, the electrode 100 d may comprise an external undercutrather than an internal undercut as described herein while remainingwithin the scope of the present invention.

As shown in FIG. 16, a fifth embodiment of the electrode indicated as100 e is preferably secured within the cathode 22 e using detents 250 asshown and described in U.S. Pat. No. 6,163,008, which is commonlyassigned with the present application and the contents of which areincorporated herein by reference. In the illustrated embodiment, thedetents 250 engage a shoulder 252 of a cap 254 secured to a distal endof the cathode 22 e as shown. Similarly, the tip 102 as shown may alsobe secured to the cartridge body 106 using detents 256, wherein thedetents 256 engage a shoulder 258 of an insulator element 260 secured toa distal end of the cartridge body 106 (not shown). As shown, thedetents 250 and 256 extend radially outward to engage the shoulders 252and 258, respectively. However, the detents 250 and 256 may alternatelyextend radially inward to engage shoulders (not shown) that extendradially outward in another form of the present invention.

Referring now to FIGS. 17 a through 17 f, additional embodiments of theelectrode 100 and the cathode 22 are illustrated, wherein cooling isprovided proximate or through an adjacent vicinity of the electricalcontact between the electrode 100 and the cathode 22 and the coolingfluid flows through at least one fluid passageway formed through theelectrode 100 and/or the cathode 10. In each of the followingembodiments, the fluid passageway may be formed in either the electrode100 or the cathode 22, depending on whether the cathode 22 is disposedwithin the electrode 100 or whether the electrode 100 is disposed aroundthe cathode 22. Accordingly, illustration and discussion of fluidpassageways through the electrode 100 shall also be construed to meanfluid passageways through the cathode 22 in alternate forms of thepresent invention and vice versa.

FIGS. 17 a and 17 b illustrate an electrode 100 f defining an extendedinner wall 251 and a cathode 22 f defining at least one spot recess 253.Accordingly, the cooling fluid flows distally through the cathode 22 fand then proximally through the spot recesses 253. Since the spotrecesses 253 are not continuous around the perimeter of the cathode 22f, the extended inner wall 251 of the electrode 100 f contacts an outerwall 23 f of the cathode 22 f as shown for the electrical contact.Therefore, the electrode 100 f and cathode 22 f define adjacentperimeter surfaces that provide both cooling and electrical contact aspreviously described.

FIG. 17 c illustrates an embodiment of a plasma arc torch 10 wherein athird element 255 is disposed between the cathode 22 g and the electrode100 g to provide both electrical contact and a fluid passageway. Thethird element 255 is in electrical contact with both the electrode 100 gand the cathode 22 g. Accordingly, the third element 255 is conductiveand allows the cooling fluid to flow proximally therethrough. Forexample, the third element 255 may comprise a canted coil spring or aporous, conductive material.

Referring now to FIG. 17 d, an electrode 100 h defines a helical flute257 for passage of the cooling fluid. The helical flute 257 is formedaround and along the interior surface of the electrode 100 h, whichresults in a plurality of ribs 259 being formed around the electrode 100h to provide the electrical contact between the electrode 100 h and thecathode 22 h. Similarly, the helical flute 257 may be formed in thecathode 22 h rather than the electrode 100 h as illustrated herein.Accordingly, the fluid passageways comprise the helical flute 257 andthe adjacent perimeter surfaces of the electrode 100 h and the cathode22 h provide both cooling and electrical contact as previouslydescribed.

As shown in another embodiment in FIG. 17 e, the electrode 100 i definesaxial passageways 259 and an annular face 261 formed in the proximal endportion of the electrode 100 i. Additionally, the cathode 22 i defines aproximal annular face 263 and a fluid passageway 265 in fluidcommunication with the axial passageways 259. Accordingly, the annularface 261 abuts the proximal annular face 263 for the electrical contactand the cooling fluid flows through the axial passageways 259 in theelectrode 100 i and through the fluid passageway 265 in the cathode 100i to provide cooling proximate the electrical contact as previouslydescribed.

Referring now to FIG. 17 f, another embodiment that provides coolingproximate the electrical contact is illustrated. As shown, the electrode100 j defines an internal chamber 267 and canted passageways 269 influid communication with the internal chamber 267. The electrode 100 jfurther defines cutouts 271 that are in fluid communication with thecanted passageways 269. In operation, the cooling fluid flows distallythrough the cathode 22 j to the internal chamber 267, then proximallythrough the canted passageways 269 and the cutouts 271 for distributionto the cartridge body 106 (not shown) as previously described.Accordingly, cooling is provided proximate the electrical contactbetween the cathode 22 j and the electrode 100 j.

Yet another embodiment of a plasma arc torch 10 that provides coolingproximate the electrical contact is illustrated in FIG. 18. As shown,the electrode 100 k is secured to the cathode 22 k through an electrodeholder 273. Generally, the electrode holder 273 is conductive anddefines the fluid passageways and is in electrical contact with thecathode 22 k, while the electrode 100 k is secured to the electrodeholder 273 using methods commonly known in the art such as a threadedconnection. The electrode holder 273 is shown defining ribs 275 andflutes 277 as previously described, however, any of the fluidpassageways as shown and described herein may be incorporated with theelectrode holder 273 while remaining within the scope of the presentinvention. Therefore, cooling is provided proximate the electricalcontact between the cathode 22 k and the electrode holder 273 ratherthan directly between the cathode 22 k and the electrode 100 k.

Tip Embodiments

The tip 102 may also comprise a variety of configurations for properfluid flow, electrical contact, and attachment as shown in FIGS. 19through 24 f. Similar to the electrode 100 and the cathode 22 aspreviously described, cooling of the tip 102 is provided proximate theelectrical contact between the tip 102 and the distal anode member 108,or an adjacent anodic element. Therefore, the terms adjacent perimetersurface, proximate, and adjacent vicinity as used in relation to theelectrical contact and cooling of the tip 102 to distal anode member 108interface shall be construed similarly as the terms used above inconnection with the electrode 100 and cathode 22.

As shown in FIGS. 19–23, one form of the tip 102 a comprises a proximalannular recess 280 having swirl holes 282 offset from a center of thetip 102 a and formed through the proximal annular recess 280.Accordingly, the plasma gas flows through the annular recess 280 and theswirl holes 282 to enter the plasma chamber 172 as previously described.Additionally, the tip 102 a comprises a distal annular recess 284 thathouses an o-ring (not shown), which seals an interface between the tip102 a and the cartridge body 106 (not shown).

As shown, the tip 102 a further comprises a plurality of flutes 288 andraised ridges 290 disposed between the flutes 288 that provide forcooling fluid passage and electrical contact with the distal anodemember 108, respectively. The cooling fluid that flows distally alongthe tip 102 a flows through the flutes 288, which produce a relativelyhigh velocity flow proximate the interface between the tip 102 a and thedistal anode member 108 for improved cooling. Additionally, the raisedridges 290 contact the distal anode member 108 to provide electricalcontinuity through the anodic members (i.e., tip 102 a, distal anodemember 108, central anode member 109) of the plasma arc torch.Accordingly, the tip 102 a and the distal anode member 108 defineadjacent perimeter surfaces as previously described, wherein bothcooling and electrical contact are provided.

Referring to FIGS. 24 a–24 d, additional embodiments of the tip 102 andthe distal anode member 108 are illustrated, wherein cooling is providedproximate or through an adjacent vicinity of the electrical contactbetween the tip 102 and the distal anode member 108 and the coolingfluid flows through at least one fluid passageway formed through the tip102 and/or the distal anode member 108. In each of the followingembodiments, the fluid passageway may be formed in either the tip 102and/or the distal anode member 108. Accordingly, illustration anddiscussion of fluid passageways through the tip 102 shall also beconstrued to mean fluid passageways through the distal anode member 108in alternate forms of the present invention and vice versa.

FIGS. 24 a and 24 b illustrate a tip 102 a defining at least one spotrecess 275 and a distal anode member 108 a defining an extended innerwall 277. Accordingly, the cooling fluid flows distally through the spotrecesses 275 since the spot recesses 275 are not continuous around theperimeter of the tip 102 b. Additionally, the extended inner wall 277 ofthe distal anode member 108 b contacts the tip 102 a as shown for theelectrical contact. Therefore, the tip 102 a and distal anode member 108a define adjacent perimeter surfaces that provide both cooling andelectrical contact as previously described.

FIG. 24 c illustrates an embodiment of a plasma arc torch 10 wherein athird element 279 is disposed between the tip 102 c and the distal anodemember 108 c to provide both electrical contact and a fluid passageway.The third element 279 is in electrical contact with both the tip 102 cand the distal anode member 108 c. Accordingly, the third element 279 isconductive and allows the cooling fluid to flow proximally therethrough.For example, the third element 279 may comprise a canted coil spring ora porous, conductive material.

Referring now to FIG. 24 d, a tip 102 c defines a helical flute 281 forpassage of the cooling fluid. The helical flute 281 is formed around andalong the exterior surface of the tip 102 c, which results in aplurality of ribs 283 being formed around the tip 102 c to provide theelectrical contact. Similarly, the helical flute 281 may be formed inthe distal anode member 108 c rather than the tip 102 c as illustratedherein. Accordingly, the fluid passageways comprise the helical flute281 and the adjacent perimeter surfaces of the tip 102 c and the distalanode member 108 c provide cooling proximate the electrical contact aspreviously described.

Additionally, a tip holder may also be employed as previously describedwith the electrode holder while remaining within the scope of thepresent invention, wherein the tip holder includes passageways for thepassage of cooling fluid proximate the electrical contact with thedistal anode member 108. Accordingly, the tip holder is an adjacentanodic element that is in electrical contact with the distal anodemember 108.

Secondary Cap and Spacer

Referring now to FIGS. 25 a and 25 b, flow of the secondary gas throughthe secondary cap 112 in one form of the present invention is swirledthrough the use of swirl passageways 300 formed in the secondary cap112. Preferably, the swirl passageways 300 are offset from a center ofthe secondary cap 112 as shown in FIG. 13 b and form a passage forsecondary gas flow between the secondary cap 112 and the shield cap 114(not shown). Alternately, the swirl passageways 300 may be formeddirectly through the secondary cap 112 as best shown in FIG. 25 b andare similarly offset from a center of the secondary cap 112.Additionally, the secondary bleed passageways 171 are illustrated asaxial holes in the embodiment as shown.

Alternately, bleed passageways may be formed in the shield cap 114 orbetween the shield cap 114 and the secondary cap 112 as shown in FIGS.26 a through 26 c. As shown in FIGS. 26 a and 26 b, secondary gas bleedpassageways 173 are preferably formed along a sidewall 175 of the shieldcap 114 and guide a portion of the secondary gas from the distalsecondary gas passage 209 along the outside of the secondary cap 112.Accordingly, the secondary gas bleed passageways 173 provide additionalcooling during operation of the plasma arc torch 10. Alternately, asecondary gas bleed passage 177 may be provided between the shield cap114 and the secondary cap 112 as shown in FIG. 26 c. Similarly, thesecondary gas bleed passage 177 guides a portion of the secondary gasfrom the distal secondary gas passage 209 along the outside of thesecondary cap 112 to provide additional cooling.

Referring now to FIGS. 27 a and 26 b, the swirl passageways 302 mayalternately be formed through the secondary spacer 116 as shown ratherthan through the secondary cap 112. The swirl passageways 302 are formedthrough a sidewall 303 of the secondary spacer 116 as shown. Further,the swirl passageways are preferably offset from a center of thesecondary spacer 116 as previously described, although otherconfigurations such as passageways formed normal through the secondaryspacer 116 may be employed to swirl the secondary gas.

Consumables Cartridge

In yet another form of the present invention, a consumables cartridge310 a is provided for efficiency and ease of replacement duringoperation as shown in FIGS. 28 a and 28 b. In one form, the consumablescartridge 310 a comprises an electrode 312, a tip 314, a spacer 316disposed between the electrode 312 and the tip 314, a cartridge body316, and an anode member 318, which are assembled and provided as asingle unit.

Referring to FIG. 29, a second embodiment of the consumables cartridge310 b is preferably secured to the plasma arc torch 10 using detents 320formed in the electrode 312 as previously described, which engage ashoulder 322 formed in an insulating cap 324. The insulating cap 324 issecured to the distal end portion of a cathode 325, and the detents 320of the electrode 312 contact the cathode 325 as shown to form a portionof the cathodic, or negative side of the power supply. Accordingly, theconsumables cartridge 310 b is easily installed and removed from theplasma arc torch 10. Alternately, the consumables cartridge 310 b may besecured to the torch 10 using a canted coil spring (not shown) aspreviously described in relation to other connections such as betweenthe central anode member 109 (not shown) and the anode body 20 (notshown).

Torch Head Connections

With reference to FIGS. 30 through 33 b, the consumables cartridge 16 issecured to an adjacent torch head 12 using either a stepped cartridgedesign (FIGS. 30, 31), a face seal design (FIGS. 32 a,b), or a straightcartridge design (FIGS. 33 a,b). As shown in FIGS. 30 (showing coolingfluid passageways) and 31 (showing gas passageways), a consumablecartridge 16 a defines a plurality of steps 352 that face proximally tomate with a corresponding set of steps 354 that face distally on thetorch head 12 a. Additionally, four (4) o-rings (not shown) seal theinterface between the consumables cartridge 16 a and the torch head 12.As a result, no rotational alignment is required between the consumablescartridge 16 a and the torch head 12 a, while ease of separation isprovided with minimum o-ring engagement.

Referring to FIGS. 32 a (showing cooling fluid passageways) and 32 b(showing gas passageways), a face seal design is alternately employedbetween a consumables cartridge 16 b and the torch head 12 b, whereino-rings 340 are disposed between proximal faces of the consumablescartridge 16 b and distal faces of the torch head 12 b as shown.Accordingly, a relatively compact torch head 12 b may be provided. Inyet another form as shown in FIGS. 33 a (showing cooling fluidpassageways) and 33 b (showing gas passageways), a straight cartridgedesign is provided wherein a series of o-rings 342 are disposedannularly between the torch head 12 c and the consumables cartridge 16c, wherein fluid passageways 344 are disposed between the o-rings 342 asshown.

In another form, consumable components are secured to a torch head usinga ball lock mechanism 360 disposed within a locking ring 17 d, which isshown in greater detail in FIGS. 34 a (connected) and 34 b(disconnected). The ball lock mechanism 360 comprises a ball 362disposed within a recess 364 when the consumable components 16 d areconnected. To disconnect the consumable components 16 d, the lockingring 17 d is moved proximally and the consumable components 16 d aremoved distally relative to the torch head such that the ball 362 movesradially outward into a locking ring recess 366. Accordingly, theconsumable components 16 d may be removed from the torch head byemploying the ball lock mechanism 160 into a locking ring 17 d.

As shown in FIGS. 35 a and 35 b, the torch head 12 e in another formdefines an alignment wall 390 to properly align the consumablecomponents 16 e with the supply of cooling fluid, plasma gas, andsecondary gas. The torch cap 70 e also defines a corresponding alignmentwall 392 that interfaces with the torch head alignment wall 390 toproperly position the torch head 12 e and consumable components 16 e foroperation.

The gases used for plasma and secondary vary according to the workpieceproperties such as material type and thickness, and may include, by wayof example N₂ as the plasma gas and H₂O as the secondary gas.Alternately, a mixture of Ar, H₂, and N₂ may be used for the plasma gaswith N₂ as the secondary gas. Additionally, the cooling fluid ispreferably an H₂O-ethylene glycol mixture or an H₂O-propylene glycolmixture.

Alternate Plasma Arc Torch Embodiment

Another form of a plasma arc torch according to the present invention isillustrated and indicated by reference numeral 410 as shown in FIGS. 36through 38. The plasma arc torch 410 comprises a torch head 412 (whichis shown in greater detail in FIG. 37) disposed at a proximal end 414 ofthe plasma arc torch 410 and a plurality of consumable components 416(shown in greater detail in FIG. 38) secured to the torch head 412 anddisposed at a distal end 418 of the plasma arc torch 410 as shown.

Torch Head

Referring more specifically to FIG. 37, the torch head 412 includes ananode body 420 that is in electrical communication with the positiveside of a power supply (not shown), and a cathode 422 that is inelectrical communication with the negative side of the power supply. Thecathode 422 is further surrounded by a central insulator 424 to insulatethe cathode 422 from the anode body 420, and similarly, the anode body420 is surrounded by an outer insulator 426 to insulate the anode body420 from a housing 428, which encapsulates and protects the torch head412 and its components from the surrounding environment duringoperation. The torch head 412 is further adjoined with a coolant supplytube 430, a plasma gas tube 432, a coolant return tube 434, and asecondary gas tube 435 as shown, wherein plasma gas and secondary gasare supplied to and cooling fluid is supplied to and returned from theplasma arc torch 410 during operation as described in greater detailbelow.

The cathode 422 preferably defines a cylindrical tube having a centralbore 436 that is in fluid communication with the coolant supply tube 430at a proximal portion 438 of the torch head 412. The central bore 436 isalso in fluid communication with a cathode cap 440 and a coolant tube442 at a distal portion 444 of the torch head 412. Generally, thecoolant tube 442 provides for the passage of cooling fluid, while thecathode cap 440 protects the end of the cathode 422. The cathode cap 440further comprises an annular shoulder 448 that engages an internalannular groove 446 within the cathode 422 to secure the cathode cap 440to the cathode 422. Preferably, the coolant tube 442 is formed of adurable material such as stainless steel, and the cathode cap 440 isinsulative and is preferably formed of a material such as Torlon® orother material known in the art that is also capable of operating atrelatively high temperatures as previously described.

The central insulator 424 preferably defines a cylindrical tube havingan internal bore 460 that houses the cathode 422 as shown. The cathode422 defines a proximal external shoulder 462 that abuts a proximalinternal shoulder 464 of the central insulator 424 to position of thecathode 422 along the central longitudinal axis X of the plasma arctorch. The central insulator 424 is further disposed within the anodebody 420 as shown along a central portion 468 and also engages a torchcap 470 that accommodates the coolant supply tube 430, the plasma gastube 432, and the coolant return tube 434.

Electrical continuity for electric signals such as a pilot return isprovided through a contact 472 disposed between the torch cap 470 andthe anode body 420. The contact 472 comprises a proximal flange 474 thatabuts a recessed shoulder 476 formed in the torch cap 470 and a distalend 478 that engages the anode body 420 as shown. Preferably, thecontact 472 is threaded into the anode body 420, however, otherattachment methods such as a press fit or soldering may also be used inaccordance with the teachings of the present invention.

Alternately, electrical continuity for the pilot return or otherelectrical signals may be provided directly through an interface betweenthe torch cap 470 and the anode body 420 using detents engaging ashoulder as shown and described in U.S. Pat. No. 6,163,008, which iscommonly assigned with the present application and the contents of whichare incorporated herein by reference. The detents may be incorporated onthe torch cap 470 or the anode body 420 with a corresponding shoulderand cap on the anode body 420 or torch cap 470, respectively. Further,the detents provide a connection that is relatively simple and easy toengage and disengage. Similarly, other connections between componentswithin the plasma arc torch 10 may also employ the detents and shoulderwhile remaining within the scope of the present invention.

Consumable Components

The consumable components 416, which are shown in greater detail in FIG.38 and also in FIG. 36, comprise an electrode 500, a tip 502, and aspacer 504 disposed between the electrode 500 and the tip 502 as shown.The spacer 504 provides electrical separation between the cathodicelectrode 500 and the anodic tip 502, and further provides certain gasdistributing functions as described in greater detail below. A tip guide503 and a tip seal 505 are disposed at the distal end portion of the tip502 as shown and provide certain cooling fluid distribution and sealingfunctions, which are also described in greater detail below.

Further, the consumable components 416 comprise a cartridge body 506that generally houses and positions the other consumable components 416and is part of a consumables cartridge, which is described in greaterdetail below. The cartridge body 506 also distributes plasma gas,secondary gas, and cooling fluid during operation of the plasma arctorch 410, as described in greater detail below. Additionally, theconsumable components 416 comprise a distal anode member 508 and acentral anode member 509 to form a portion of the anodic side of thepower supply by providing electrical continuity to the tip 502. A baffle510 is also shown disposed between the distal anode member 508 and ashield cap 514, which forms fluid passageways for the flow of a coolingfluid as described in greater detail below. Further, the consumablecomponents 416 comprise a secondary cap 512 for the distribution of thesecondary gas and a secondary spacer 516 that separates the secondarycap 512 from the tip 502 and directs the flow of secondary gas. Alocking ring 517 is shown disposed around the proximal end portion ofthe consumable components 416, which is used to secure the consumablecomponents 416 to the torch head 412.

The electrode 500 is centrally disposed within the cartridge body 506and is in electrical contact with the cathode 422 along an interiorportion 518 of the electrode 500 as described in greater detail below.The electrode 500 further defines a distal cavity 520 that is in fluidcommunication with the coolant tube 442 and an external shoulder 522that abuts the spacer 504 for proper positioning along the centrallongitudinal axis X of the plasma arc torch 410. The electrode 500further comprises at least one passageway for the passage of coolingfluid proximate the electrical contact with the cathode 422. Morespecifically, the electrode 500 preferably comprises a plurality of ribs521 and a corresponding plurality of flutes 523 disposed between theribs 521, wherein the ribs 521 provide electrical contact with thecathode 422 and the flutes 523 provide for the passage of a coolingfluid as previously described in relation to the first plasma arc torch10 embodiment. Accordingly, the electrode 500 and the cathode 422 defineadjacent perimeter surfaces as previously described such that cooling ofthe electrode 500 is provided proximate, or through an adjacent vicinityof, the electrical contact between the electrode 500 and the cathode422. Alternately, the electrode 500 and cathode 422 may comprise otherembodiments as previously described, wherein at least one fluidpassageway is formed proximate the electrical contact for propercooling.

The cartridge body 506 further comprises an internal annular ring 524that abuts a proximal end 526 of the electrode 500 for properpositioning of the electrode 500 along the central longitudinal axis Xof the plasma arc torch 410. Additionally, the connection between thecartridge body 506 and the cathode 422 may employ the detents andshoulder as previously described while remaining within the scope of thepresent invention. In addition to positioning the various consumablecomponents 416, the cartridge body 506 also separates anodic members(e.g., central anode member 509) from cathodic members (e.g., electrode500). Accordingly, the cartridge body 506 is an insulative material suchas PEEK® or other similar material commonly known in the art that isfurther capable of operating at relatively high temperatures.

Referring to FIGS. 38 and FIGS. 39 a through 39 d, the cartridge body506 provides for the distribution of cooling fluid, plasma gas, andsecondary gas, in addition to positioning the other consumablecomponents 416. For the distribution of cooling fluid, which isdescribed in greater detail below, the cartridge body 506 defines acentral chamber 528 and a plurality of passageways 530 that extendthrough the cartridge body 506 and into an inner cooling chamber 532formed between the cartridge body 506 and the distal anode member 508.Preferably, the passageways 530 are angled radially outward in thedistal direction from the upper chamber 528 to minimize any dielectriccreep that may occur between the electrode 500 and the distal anodemember 508. Additionally, outer axial passageways 533 (shown dashed) areformed in the cartridge body 506 that provide for a return of thecooling fluid. The outer axial passageways 533 are also positioned alongthe distal anode member 508 and the central anode member 509 andproximate the electrical interface therebetween. Accordingly, theposition of the outer axial passageways 533 provides improved cooling ofthe distal anode member 508 and the central anode member 509. Near thedistal end of the consumables cartridge 416, an outer fluid passage 548is formed between the distal anode member 508 and the baffle 510.Accordingly, the outer fluid passage 548 is in communication with theouter axial passageways 533 for the return of cooling fluid which isdescribed in greater detail below.

For the distribution of plasma gas, the cartridge body 506 defines aplurality of distal axial passageways 534 (shown dashed in FIG. 38) thatextend from a proximal face 536 of the cartridge body 506 to a distalend 538 thereof, which are in fluid communication with the plasma gastube 532 (not shown) and passageways formed in the spacer 504 asdescribed in greater detail below. Additionally, a plurality of proximalaxial passageways 540 (shown dashed in FIG. 38) are formed through thecartridge body 506 that extend from a recessed proximal face 542 to adistal outer face 544 for the distribution of a secondary gas, which isalso described in greater detail below. Moreover, the cartridge body 506defines a scalloped proximal periphery 507 that provides for ease of fitof the cartridge body 506 within the torch head 412.

As shown in FIGS. 36 and 38, the distal anode member 508 is disposedbetween the cartridge body 506 and the baffle 510 and is in electricalcontact with the tip 502 at a distal portion and with the central anodemember 509 at a proximal portion. Further, the central anode member 509is in electrical contact with a distal end portion 546 of the anode body420. Preferably, the central anode member 509 comprises a plurality offingers 547 (best shown in FIG. 40) defining detents 549 at a proximalend thereof to provide secure electrical contact between the centralanode member 509 and the anode body 420. As shown, the detents 549extend over a shoulder 551 formed on a distal sleeve 553 disposed overthe distal end portion 546 of the anode body 420. The distal sleeve 553is preferably formed of an insulative material such as ULTEM® and ispress fit over the distal end portion 546 of the anode body 420. Thedetents 549 are similar to those disclosed in U.S. Pat. No. 6,163,008,which is commonly assigned with the present application and the contentsof which are incorporated herein by reference. The detents 549 may beincorporated on the central anode member 509 or the anode body 420 witha corresponding shoulder and cap on the anode body 420 or central anodemember 509, respectively. Accordingly, the anode body 420, the distalanode member 508, the central anode member 509, and the tip 502 form theanode, or positive, potential for the plasma arc torch 410.

Referring to FIGS. 36, 38, and 41, axial tabs 566 are formed in thedistal anode member 508, wherein the axial tabs 566 similarly definedetents 567 and are biased inward as shown to provide electricalcontinuity between the distal anode member 508 and the central anodemember 509. The proximal end portion of the distal anode member 508defines an extended upper wall 569 that extends outwardly as shown toposition the axial tabs 566 around the central anode member 509. Asfurther shown, a retention ring 571 is disposed around a central portionof the cartridge body 506 to retain and position the central anodemember 509 along the central longitudinal axis X of the plasma arc torch410. Accordingly, the axial tabs 566 and the extended upper wall 569extend over the retention ring 571 to make electrical contact with thecentral anode member 509.

Referring to FIGS. 36 and 38, the shield cap 514 surrounds the baffle510 as shown, wherein a secondary gas passage 550 is formedtherebetween. Generally, the secondary gas flows from the proximal axialpassageways 540 formed in the cartridge body 506 into the secondary gaspassage 550 and through the secondary cap 512, as described in greaterdetail below, to stabilize the plasma stream exiting the secondary cap512 in operation. The shield cap 514 further positions the secondary cap512, wherein the secondary cap 512 defines an annular shoulder 552 thatengages an internal shoulder 554 of the shield cap 514.

The secondary spacer 516 spaces and insulates the secondary cap 512 fromthe tip 502 and also distributes secondary gas to stabilize the plasmastream during operation. Preferably, the secondary spacer 516 comprisesa proximal face 556 that abuts an annular shoulder 558 of the tip seal505 and a distal face 560 and shoulder 562 that abut an internalshoulder 564 and proximal face 573, respectively, of the secondary cap512. As further shown, the secondary spacer 516 forms a secondary gaschamber 578 between the tip seal 505 and the secondary cap 512, whereinthe secondary gas is distributed to stabilize the plasma stream, asdescribed in greater detail below. Accordingly, the secondary spacer 516defines secondary gas passageways 513 as previously described thatdirect and preferably swirl the flow of secondary gas into the secondarygas chamber 578. The secondary cap 512 further comprises a central exitorifice 568 through which the plasma stream exits and a recessed face570 that contributes to controlling the plasma stream.

As shown in FIGS. 38 and 42, the tip guide 503 and tip seal 505 aredisposed at the distal end portion of the tip 502. The tip 502 comprisesa conical end portion 577 that defines a plurality of flutes 579 andraised ridges 581, as previously described in other tip embodiments,wherein the raised ridges 581 contact the distal end portion of thedistal anode member 508 for electrical contact and the flutes 579provide fluid passageways for the passage of cooling fluid duringoperation as described in greater detail below. Accordingly, a distalfluid passageway 580 is formed between the tip 502 and the tip guide 503and also between the tip guide 503 and the tip seal 503, wherein the tipguide 503 guides the cooling fluid distally past the tip 502 and thenproximally for recirculation of the cooling fluid that is described ingreater detail below.

As best shown in FIG. 42, the tip guide 503 defines radial tabs 583 thatare positioned within the flutes 579 to properly guide the cooling fluidduring operation. The tip guide 503 also comprises a conical end wall585 that is shaped to conform to the conical end portion 577 of the tip502. As further shown, the tip seal 505 also defines a conical endportion 587 to conform to the tip guide 503, which results in theformation of the distal fluid passageway 580. Preferably, the tip guide503 is a brass material, and the tip seal 505 and the tip 502 are atellurium copper material.

Referring now to FIG. 38 and FIG. 43, the tip 502 further comprises feet589 and offset feet 591, wherein the feet 589 extend distally beyond theoffset feet 591 as shown. When assembled to the tip seal 505, the feet589 engage an upper annular face 601 of the tip seal 505 and a gap 603is produced between the offset feet 591 and the upper annular face 601of the tip seal 505. Accordingly, the gap 603 provides additional spacefor the flow of cooling fluid that is being returned for recirculation.As further shown, the tip defines a distal face 605 that engages aninternal annular shoulder 605 of the tip seal 505 to further positionthe tip 502 relative to the tip seal 505.

As shown in FIG. 38, the tip 502 is electrically separated from theelectrode 500 by the spacer 504, which results in a plasma chamber 572being formed between the electrode 500 and the tip 502. The spacer 504defines swirl passageways 607 (shown dashed) that swirl the plasma gasflowing from the distal axial passageways 534 into the plasma chamber572. The tip 102 further comprises a central exit orifice 574, throughwhich a plasma stream exits during operation of the plasma arc torch 410as the plasma gas is ionized within the plasma chamber 572, which isdescribed in greater detail below.

As further shown, the locking ring 517 secures the consumable components416 to the torch head 412 when the plasma arc torch 410 is fullyassembled. The locking ring 517 is preferably secured to the torch head412 through a threaded connection, wherein the locking ring 517comprises a threaded insert 519. Preferably, the threaded insert 519 isbrass and the locking ring 517 is a thermoset material that isovermolded onto the threaded insert 519. Alternately, the consumablecomponents 416 may be secured to the torch head 412 using a dual pitchlocking connector as shown and described in copending application Ser.No. 10/035,534 filed Nov. 9, 2001, which is commonly assigned with thepresent application and the contents of which are incorporated herein byreference.

Cooling Fluid Flow

Referring to FIG. 44, in operation, the cooling fluid flows from thecoolant supply tube 430, distally through the central bore 436 of thecathode 422, through the coolant tube 442, and into the distal cavity520 of the electrode 500. The cooling fluid then flows proximallythrough the proximal cavity 518 formed between the flutes 523 of theelectrode 500 and the cathode 422 to provide cooling to the electrode500 and the cathode 422 that are operated at relatively high currentsand temperatures. The cooling fluid continues to flow proximally to thepassageways 530 in the cartridge body 506, wherein the cooling fluidthen flows through the passageways 530 and into the inner coolingchamber 532. The cooling fluid then flows past the tip 502, which alsooperates at relatively high temperatures, in order to provide cooling tothe tip 502. More specifically, the cooling fluid flows through thedistal fluid passageway 580 formed by the tip guide 503 between the tip502 and the tip seal 505. The cooling fluid first flows distally throughthe flutes 579 of the tip 502 and then reverses direction around thedistal end of the tip guide 503 to then flow proximally through thedistal fluid passageway 580 between the tip guide 503 and the tip seal505. The cooling fluid then flows proximally through the outer fluidpassage 548 formed between the distal anode member 508 and the baffle510 and through the outer axial passageways 533 (shown dashed) in thecartridge body 506. The cooling fluid then flows proximally throughrecessed walls 590 and axial passageways 592 formed in the anode body420. Once the cooling fluid reaches a proximal shoulder 593 of the anodebody 420, the fluid flows through the coolant return tube 434 and isrecirculated for distribution back through the coolant supply tube 430.

As a result, the cooling fluid flow is “coaxial” as previously describedfor improved cooling and operation of the plasma arc torch 410.Therefore, the cooling fluid flow is distributed circumferentially aboutthe central longitudinal axis X of the plasma arc torch 410 and isflowing in the same direction at any radial location from the centrallongitudinal axis X to produce the coaxial flow.

Plasma Gas Flow

Referring to FIG. 45, the plasma gas generally flows distally from theplasma gas tube 432, through the torch cap 470, and into a centralcavity 596 formed in the anode body 420. The plasma gas then flowsdistally through recessed annular walls 425 (shown dashed) of thecentral insulator 424 and into the distal axial passageways 534 (showndashed) formed in the cartridge body 506. The plasma gas then flowsthrough the swirl passageways 607 (shown dashed) formed in the spacer504 between the electrode 500 and the tip 502. The plasma gas thenenters the plasma chamber 572 to form a plasma stream as the plasma gasis ionized by the pilot arc, and the plasma stream exits the centralexit orifice 574 of the tip 502 and the central exit orifice 568 of thesecondary cap 512. Additionally, the plasma gas flow is coaxial, aspreviously described, wherein the plasma gas is distributedcircumferentially about the central longitudinal axis of the torch andis flowing in the same direction at any radial location from the centrallongitudinal axis.

Secondary Gas Flow

Referring to FIGS. 36 through 38, the secondary gas generally flowsdistally from the secondary gas tube 435 (shown dashed) and through anaxial passage 602 (shown dashed) formed through the torch cap 470. Thesecondary gas then flows radially outward through an annular chamber 595(shown dashed) between the torch cap 470 and the anode body 420 andcontinues to flow distally into an outer chamber 610 formed between thetorch cap 470 and the housing 428. The secondary gas then flows throughthe axial passageways 606 formed through an annular extension 608 of theouter insulator 426, and into the proximal axial passageways 540 (showndashed) of the cartridge body 506. The secondary gas then enters thesecondary gas passage 550 and flows distally between the baffle 510 andthe shield cap 514, through the distal secondary gas passage 609, andthrough the secondary gas passageways 513 formed in the secondary spacer516. The secondary gas then enters the secondary gas chamber 578 betweenthe tip seal 505 and the secondary cap 512 to stabilize the plasmastream that exits from the central exit orifice 574 of the tip 502.Additionally, the secondary gas flow is coaxial, as previouslydescribed, wherein the secondary gas is distributed circumferentiallyabout the central longitudinal axis of the torch and is flowing in thesame direction at any radial location from the central longitudinalaxis.

Operation

In operation, with reference to FIGS. 36 and FIGS. 44–46, the cathode ornegative potential is carried by the cathode 422 and the electrode 500,and the anode or positive potential is carried by the anode body 420,the central anode member 509, the distal anode member 508, and the tip502, such that when electric power is applied to the plasma arc torch410, a pilot arc is generated in the gap formed between the electrode500 and the tip 502, within the plasma chamber 572. As the plasma gasenters the plasma chamber 572, the plasma gas is ionized by the pilotarc, which cause a plasma stream to form within the plasma chamber 572and to flow distally through the central exit orifice 574 of the tip502. Additionally, the secondary gas flows into the secondary gaschamber 578 and stabilizes the plasma stream upon exiting the centralexit orifice 574 of the tip 502. As a result, a highly uniform andstable plasma stream exits the central exit orifice 568 of the secondarycap 512 for high current, high tolerance cutting operations.

The plasma arc torch 410 also comprises a plurality of o-rings andcorresponding o-ring slots as shown in FIGS. 36 through 38, which arenot numbered herein for purposes of clarity. The o-rings generally sealthe fluid passageways, namely, the passageways for cooling fluid, plasmagas, and secondary gas during operation of the plasma arc torch, whichshould be understood by one having ordinary skill in the art.

Consumables Cartridge

Referring to FIGS. 47 a through 47 f, the present invention provides aconsumables cartridge 650 that generally comprises the cartridge body506 and at least one other consumable component. For example, as shownin FIG. 47 a, the consumables cartridge 650 a comprises the centralanode member 509, the electrode 500, the tip 502, the spacer 504, thedistal anode member 508, the shield cup 514, the baffle 510, the tipguide 503, the tip seal 505, the secondary cap 512, the secondary spacer516, and the locking ring 517, along with the series of o-rings asshown. With the use of the consumables cartridge 650, the entirecartridge 650 is replaced when one or more consumable components requirereplacement to provide for a quick and efficient replacement ofconsumable components rather than replacing individual consumablecomponents one at a time.

As shown in FIG. 47 b, the consumables cartridge 650 b comprises thecentral anode member 509, the electrode 500, the tip 502, the spacer504, the distal anode member 508, the shield cup 514, the baffle 510,the tip guide 503, the tip seal 505, the secondary cap 512, and thesecondary spacer 516. The consumables cartridge 650 c in FIG. 47 ccomprises the central anode member 508 and the locking ring 517. Theconsumables cartridge 650 d illustrated in FIG. 47 d comprises theelectrode 500, the tip 502, the spacer 504, the tip guide 503, the tipseal 505, the secondary cap 512, and the secondary spacer 516.

Referring to FIG. 47 e, the consumables cartridge 650 e comprises theelectrode 500, the tip 502, the spacer 504, the secondary cap 512, andthe secondary spacer 516. Alternately, the consumables cartridge 650 fin FIG. 47 f comprises the central anode member 509, the electrode 500,the tip 502, the spacer 504, the distal anode member 508, the shield cup514, the baffle 510, the secondary cap 512, and the secondary spacer516. Other combinations of consumables components may also be employedaccording to the teachings of the present invention and the specificembodiments illustrated herein should not be construed as limiting thescope of the present invention. Moreover, o-rings may be included asshown in some of the consumables cartridges 650 for sealing duringoperation of the plasma arc torch.

Assemblies

Referring to FIGS. 48 a through 48 g, specific assemblies of consumablecomponents are preferably provided by the present invention for ease ofassembly and support of the plasma arc torch 410. For example, anassembly of the shield cup 514, the baffle 510, and the distal anodeshield 508 is shown in FIG. 48 a as a shield cup assembly 660.Preferably, the shield cup assembly 660 is provided to an end user as acompleted assembly, wherein the shield cup 514, the baffle 510, and thedistal anode shield 508 are preferably secured to one another through aninterference fit. Additionally, FIG. 48 b illustrates a tip assembly662, which comprises the tip 502 and the tip guide 503. Another tipassembly 664 is shown in FIG. 48 c, which comprises the tip 502, the tipguide 503, and the tip seal 505.

Referring to FIG. 48 d, a secondary spacer assembly 666 is illustratedthat includes the tip guide 505, the secondary spacer 516, and thesecondary cap 512. An electrode assembly 668 is shown in FIG. 48 e andcomprises the electrode 500 and the spacer 504. Further, one cartridgeassembly 670 is shown in FIG. 48 f and comprises the cartridge body 506,the central anode member 509, and the locking ring 517. Anothercartridge assembly 672 is shown in FIG. 48 g and comprises the cartridgebody 506 and the central anode member 509. Other combinations ofassemblies may also be employed according to the teachings of thepresent invention and the specific embodiments illustrated herein shouldnot be construed as limiting the scope of the present invention.Moreover, o-rings may be included as shown in some of the assemblies forsealing during operation of the plasma arc torch.

As used herein, the consumables cartridges and assemblies should beconstrued to include all possible combinations of embodiments ofconsumable components described herein. Accordingly, the consumablescartridges and assemblies disclosed herein should not be construed asbeing limited to the consumable components disclosed as a part of thespecific plasma arc torch 410.

Torch Head Connections

Referring now to FIG. 49, the consumable components 416 are secured tothe torch head 412 using the locking ring 517 and a threaded connectionas previously described. When fully assembled, a distal face 680 of theouter insulator 426 is disposed adjacent the recessed proximal face 542of the cartridge body 506. Accordingly, an annular chamber 682 is formedbetween the distal face 680 of the outer insulator 426 and the recessedproximal face 542 of the cartridge body. Therefore, the secondary gasthat flows through the axial passageways 606 of the outer insulator 426is distributed around the annular chamber 682 for passage through theproximal axial passageways 540 (shown dashed) of the cartridge body 506.As a result, the secondary gas flows between the torch head 412 and theconsumable components 416 independent of rotational alignment of theconsumable components 416 with respect to the torch head 412.

Similarly, the recessed annular walls 425 of the central insulator 424are disposed adjacent the proximal face 536 of the cartridge body 506.Accordingly, an annular chamber 692 is formed between the recessedannular walls 425 of the central insulator 424 and the proximal face 536of the cartridge body 506.

Therefore, the plasma gas that flows through the recessed annular walls425 of the central insulator 424 is distributed around the annularchamber 692 for passage through the distal axial passageways 534 (showndashed) formed in the cartridge body 506. As a result, the secondary gasflows between the torch head 412 and the consumable components 416independent of rotational alignment of the consumable components 416with respect to the torch head 412.

Similar to the secondary gas and plasma gas flows, the torch headconnection independent of rotational alignment is also provided with thecooling fluid flow return. As shown, an outer distal face 700 of theanode body 420 is disposed adjacent an outer proximal face 702 of thecartridge body 506. Accordingly, an annular chamber 704 is formedbetween the outer distal face 700 of the anode body 420 and the outerproximal face 702 of the cartridge body 506. Therefore, the coolingfluid that flows through outer axial passageways 533 (shown dashed) inthe cartridge body 506 is distributed around the annular chamber 704 forpassage through the recessed walls 590 (shown dashed) and axialpassageways 592 (shown dashed) formed in the anode body 420. As aresult, the cooling fluid flows between the consumable components 416and the torch head 412 independent of rotational alignment of theconsumable components 416 with respect to the torch head 412.

Accordingly, a proximal element (e.g., anode body 420, outer insulator426) and a distal element (e.g., cartridge body 506) are configured todefine at least one chamber when the proximal and distal elements areengaged. The chamber is in fluid communication with at least one fluidpassage through the proximal element and at least one fluid passage inthe distal element to make a fluid connection between the fluid passagesindependent of the rotational alignment of the proximal and distalelements.

Additionally, a pilot return 800 is disposed at a proximal end portionof the plasma arc torch 410 and is in face contact with the anode body420 such that an electrical connection is also made independent ofrotational alignment of the consumable components 416. Further, theelectrical connection between the central anode member 509 and the anodebody 420 is also made independent of rotational alignment with the useof the detents 549 on the central anode member 509. Accordingly, bothelectrical connections and fluid connections are provided by the presentinvention that are independent of rotational alignment.

It should be understood that the torch head connection described hereinmay also be employed with other plasma arc torch embodiments describedherein. Additionally, the torch head connections as previously describedsuch as the stepped cartridge design (FIGS. 30, 31), the face sealdesign (FIGS. 32 a,b), the straight cartridge design (FIGS. 33 a,b), orthe ball lock mechanism (FIGS. 34 a,b) may also be employed with thevarious plasma arc torch embodiments disclosed herein while remainingwithin the scope of the present invention. Accordingly, the torch headconnections should not be construed as being limited to any specificplasma arc torch embodiment such as the plasma arc torch 410.

Additionally, each of the consumable component embodiments describedherein (e.g., electrodes 100 a through 100 k, tips 102 a through 102 c,among others) should not be limited in application to the specificplasma arc torch embodiment in which they are described. For example,any of the electrode embodiments may be employed in the alternate plasmaarc torch 410 while remaining within the scope of the present invention.Accordingly, each of the embodiments of the present invention may beemployed on any plasma arc torch disclosed herein while remaining withinthe scope of the present invention.

Alternate Plasma Arc Torch Embodiment

Yet another form of a plasma arc torch according to the presentinvention is illustrated and indicated by reference numeral 810 as shownin FIG. 50. (Only certain consumable components of the plasma arc torch810 are illustrated for purposes of clarity). The operation of theplasma arc torch 810 is substantially similar to those previouslydescribed with the coaxial flow, distribution of plasma and secondarygases, various consumable component embodiments, and the use of aconsumables cartridge, assemblies, and torch head connections. However,the plasma arc torch 810 also comprises a dielectric spacer 812 betweenthe electrode 814 and the tip 816 as shown. The dielectric spacer 812 isdisposed within the spacer 818 that spaces and insulates the electrode814 from the tip 816 as previously described. Accordingly, thedielectric spacer 812 increases the dielectric between the cathodicelectrode 814 and the anodic tip 816 so that the pilot arc is notgenerated near the proximal end of the tip 816 between the electrode 814and the tip 816 as indicated by numeral 820. Rather, the pilot arc isformed near the distal end portion of the electrode 814 as indicated bynumeral 822. Preferably, the dielectric spacer 812 is formed of aFluorosint® material.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the substance of the inventionare intended to be within the scope of the invention. For example, asshown in FIG. 51, the various embodiments of the invention as disclosedherein may be employed in a plasma arc torch 910 within a plasma arctorch cutting system 912 that includes a fluid control system 914, amotion control system 916, an arc starter 918, and/or a central controlsystem 920 while remaining within the scope of the present invention.Such variations are not to be regarded as a departure from the spiritand scope of the invention.

1. A tip configured for electrical contact and passage of a fluidbetween the tip and an adjacent anodic element of a plasma arc torch,the tip comprising a perimeter surface adjacent a perimeter surface ofthe anodic element, wherein the adjacent perimeter surfaces provide theelectrical contact and the passage of the fluid.
 2. The tip according toclaim 1 wherein the tip further comprises at least one passageway. 3.The tip according to claim 2 wherein the passageway comprises at leastone spot recess formed in the tip.
 4. The tip according to claim 2wherein the passageway comprises helical flutes formed in the tip. 5.The tip according to claim 2 wherein the passageway comprises an axialpassageway formed in the tip.
 6. The tip according to claim 1 whereinthe tip further comprises at least one flute for passage of the fluidand at least one raised ridge for electrical contact.
 7. The tipaccording to claim 6 wherein the flutes and raised ridges are disposedalong an exterior portion of the tip.
 8. The tip according to claim 7wherein the flutes and the raised ridges are evenly spaced around adistal end portion of the tip.
 9. The tip according to claim 1 whereinthe tip further comprises a recess defining passageways that direct aplasma gas.
 10. The tip according to claim 1 wherein the tip furthercomprises a detent for connection to an adjacent component of the plasmaarc torch.
 11. A tip for use in a plasma arc torch, the tip beingconfigured for coaxial fluid flow, the coaxial fluid flow including adistal flow flowing distally to the tip and a proximal flow flowingproximally from the tip, the tip guiding the distal flow into a proximalflow outside a distal end of the tip.
 12. The tip according to claim 11wherein the tip is further configured for electrical contact with anadjacent anodic element and the fluid flows proximate the electricalcontact.
 13. The tip according to claim 12 wherein the tip furthercomprises at least one passageway for passage of the fluid.
 14. A tipconfigured for electrical contact with an anodic element of a plasma arctorch, the tip comprising at least one passageway and a perimetersurface adjacent a perimeter surface of the anodic element, wherein acooling fluid passes through the passageway for cooling proximate theelectrical contact and the adjacent perimeter surfaces provide theelectrical contact.
 15. A liquid cooled tip configured for electricalcontact with an anodic element of a plasma arc torch, the anodic elementpositioned at a distal end of the tip, the tip comprising at least onepassageway formed between the distal end of the tip and the anodicelement for passage of the liquid.
 16. A tip configured for electricalcontact with an anodic element of a plasma arc torch and passage of acooling fluid proximate the electrical contact, the tip comprising: atleast one flute; and at least one raised ridge disposed adjacent theflute, wherein the raised ridge contacts the anodic element for theelectrical contact and the cooling fluid passes through the flute forcooling proximate the electrical contact.
 17. A tip configured forelectrical contact with an anodic element of a plasma arc torch andpassage of a cooling fluid proximate the electrical contact, the tipcomprising: a plurality of flutes; and a plurality of raised ridgesdisposed between the flutes, wherein the raised ridges contact theanodic element for the electrical contact and the cooling fluid passesthrough the flutes for cooling proximate the electrical contact.
 18. Aliquid cooled tip configured for electrical contact with an anodicelement of a plasma arc torch and passage of a cooling fluid for coolingproximate the electrical contact, the tip comprising: a plurality ofexternal raised ridges; and a plurality of external flutes disposedbetween the raised ridges, wherein the raised ridges provide theelectrical contact with the anodic element and provide for at least aportion of the flow of cooling fluid, and the plurality of flutesprovide at least a portion of the flow of the cooling fluid.
 19. The tipaccording to claim 18 wherein the tip further comprises a plurality offeet and offset feet disposed at a distal end portion tip, wherein theoffset feet provide for improved cooling of the tip.
 20. A tip for usein a plasma arc torch comprising: a means for conducting electric powerbetween adjacent perimeter surfaces of the tip and an adjacent anodicelement; and a means for conducting fluid between the adjacent perimetersurfaces of the tip and the adjacent anodic element proximate the meansfor conducting electric power.
 21. A plasma arc torch comprising: ananodic element defining a perimeter surface; and a tip configured forelectrical contact with the anodic element and passage of a fluidbetween the tip and the anodic element, the tip defining a perimetersurface adjacent the perimeter surface of the anodic element, whereinthe adjacent perimeter surfaces provide the electrical contact and thepassage of the fluid.
 22. The plasma arc torch according to claim 21wherein the plasma arc torch further comprises at least one passageway.23. The plasma arc torch according to claim 22 wherein the passagewaycomprises flutes formed in the anodic element.
 24. The plasma arc torchaccording to claim 22 wherein the passageway comprises flutes formed onthe anodic element and the tip.
 25. The plasma arc torch according toclaim 22 wherein the passageway comprises at least one spot recessformed in the tip.
 26. The plasma arc torch according to claim 22wherein the passageway comprises a third element disposed between tipand the anodic element.
 27. The plasma arc torch according to claim 26wherein the third element is a porous and conductive material.
 28. Theplasma arc torch according to claim 27 wherein the third element is acanted coil spring.
 29. The plasma arc torch according to claim 22wherein the passageway comprises helical flutes formed in the tip. 30.The plasma arc torch according to claim 22 wherein the passagewaycomprises an axial passageway formed in the tip.
 31. The plasma arctorch according to claim 22 wherein the passageway comprises an axialpassageway formed in the anodic element.
 32. The plasma arc torchaccording to claim 21 wherein the tip further comprises at least oneflute and at least one raised ridge.
 33. The plasma arc torch accordingto claim 32 wherein the flutes and raised ridges are disposed along anexterior portion of the tip.
 34. The plasma arc torch according to claim32 wherein the flutes and the raised ridges are evenly spaced around adistal end portion of the tip.
 35. The plasma arc torch according toclaim 32 wherein the flutes provide cooling to the orifice.
 36. Theplasma arc torch according to claim 21 wherein the tip further comprisesa recess defining passageways that direct a plasma gas.
 37. The plasmaarc torch according to claim 21 wherein the tip further comprises adetent for connection to an adjacent component of the plasma arc torch.38. A plasma arc torch comprising: an anodic element; and a tip disposedadjacent the anodic element and configured for coaxial fluid flow,wherein the fluid is guided by the tip to flow distally to outside of adistal end of the tip and then flow proximally from the tip.
 39. Aplasma arc torch comprising: an anodic element defining a perimetersurface; and a tip configured for electrical contact with the anodicelement, the tip comprising at least one passageway and a perimetersurface adjacent the perimeter surface of the anodic element, wherein acooling fluid passes through the passageway for cooling proximate theelectrical contact and the adjacent perimeter surfaces provide theelectrical contact.
 40. A plasma arc torch comprising: an anodicelement; and a liquid cooled tip configured for electrical contact withthe anodic element positioned at a distal end of the liquid cooled tip,the tip comprising at least one passageway formed between the anodicelement and the distal end of the tip for passage of the liquid.
 41. Aplasma arc torch comprising: an anodic element; and a tip configured forelectrical contact with the anodic element and passage of a coolingfluid proximate the electrical contact, the tip comprising: at least oneflute; and at least one raised ridge disposed adjacent the flute,wherein the raised ridge contacts the anodic element for the electricalcontact and the cooling fluid passes through the flute for coolingproximate the electrical contact.
 42. A plasma arc torch comprising: ananodic element; a tip holder disposed at a distal end portion of theanodic element, the tip holder in electrical contact with the anodicelement; and a tip configured for electrical contact with the tipholder, wherein a cooling fluid passes through the tip holder and alongan adjacent vicinity of the electrical contact between the tip holderand the tip.
 43. A method of operating a plasma arc torch, the methodcomprising the step of: conducting a cooling fluid and electric powerbetween adjacent perimeter surfaces of a tip and an adjacent anodicelement, wherein the adjacent perimeter surfaces provide the electricalcontact and the passage of the fluid.
 44. A method of operating a plasmaarc torch, the method comprising the step of: conducting a fluidcoaxially between a tip and an adjacent anodic element, wherein thefluid is guided by the tip to flow distally to outside of a distal endof the tip and then flow proximally from the tip.
 45. A method ofoperating a plasma arc torch, the method comprising the steps of:conducting a cooling fluid through at least one passageway defined alonga tip; and conducting electric power along adjacent perimeter surfacesof the tip and an adjacent anodic element, wherein the cooling fluidpasses through the passageway for cooling proximate the electricalcontact and the adjacent perimeter surfaces provide the electricalcontact.
 46. A method of operating a liquid cooled plasma arc torch, themethod comprising the steps of: conducting electric power between a tipand an adjacent anodic element positioned at a distal end of the tip;and conducting a liquid through at least one passageway formed betweenthe distal end of the tip and the anodic element.
 47. A method ofoperating a plasma arc torch, the method comprising the steps of:conducting a cooling fluid through a plurality of flutes defined along atip proximate an electrical connection between the tip and an adjacentanodic element; and conducting electric power through a plurality ofribs disposed between the plurality of flutes, wherein the ribs are inelectrical contact with the anodic element.